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Advanced7 min read

Root Cause Analysis (RCA)

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Root Cause Analysis identifies the underlying cause of defects rather than just fixing the symptom. Systematic RCA transforms reactive bug-fixing into proactive quality improvement, preventing entire classes of defects from recurring.

Key Points

  • 5 Whys technique: ask 'why?' five times to peel back symptoms and reach the root cause.
  • Fishbone (Ishikawa) diagram: categorises root causes into People, Process, Tools, Environment, and Code.
  • Focus RCA on escaped defects (found by customers) and high-severity defects — these have the highest learning value.
  • RCA output: immediate fix + corrective action to prevent recurrence + process improvement recommendation.
  • Track whether corrective actions are actually implemented — RCA without follow-through is theatre.
Expert Pro Tip

The most common root causes in software are: missing requirements, insufficient unit testing, and poor code review. Fix your process, not just your code.